The present disclosure relates generally to an ink set and a method for making the same.
An ink set may be used as an ink source for an inkjet printing system to produce images on a print substrate or media. Ink sets generally include two or more inks, each of which has a different color, or a different shade of the same color. Ink sets having a variety of different colored inks are often used to produce colored images. Ink sets including different shades of gray and/or black inks are often used to produce high quality black-and-white images or to improve color balance of color images. For example, an ink set may be a three ink set including a light gray ink, a medium gray ink, and a black ink. Two or more of the inks of this type of ink set may be combined together to form other shades of gray.
Production of relatively high quality black-and-white images on a print surface generally requires that the individual inks have suitable physical properties including desirable levels of neutrality, metamerism, grain control, bronzing, dynamic range, permanence, durability (e.g., waterfastness (stability to water drip) and smudgefastness (stability to smudge/abrasion)), gloss uniformity, and the like.
Several methods have been used to optimize these ink performance properties for pigmented ink systems. One example of such a method includes the addition of a gloss enhancer to the ink set to reduce bronzing and improve gloss. The gloss enhancer is printed in conjunction with the other colors to improve their gloss and bronzing performance. This method, however, requires the addition of another ink to the ink set.
Another example of such a method includes using significant amounts of cyan ink, magenta ink, and yellow ink (commonly referred to as composite black) along with, or in substitution of gray ink to reduce bronzing of the gray ink and to obtain neutrality and gloss uniformity. This method may involve the potential drawback of adding metamerism, and may involve neutrality issues.
In another example, black and gray inks may include cyan and magenta or cyan and violet colorants as shading agents (black colorants, in particular, those based on carbon black, tend to exhibit a brownish color when printed) to form a more spectrally flat gray color. Bronzing may still be a problem for images printed with this system.
In still another effort to reduce bronzing and obtain neutrality, only opaque inks (e.g., black ink, dark cyan ink, dark magenta ink, etc.) are used. Opaque inks, unlike transparent inks (e.g., gray ink, light cyan ink, light magenta ink, etc.), tend to have limited bronzing effect because they substantially eliminate reflection off of the print media.